[Cookie Monster]

??

 

[Cookie Monster]

uh, forgive my noob terminologies. By forward I mean the opposite of warm

 

[FallenAngel]

It's not very warm; AD8397 has always sounded kind of sharp to me.

 

[m0b1liz3]

So what portable amp sounds warm? Or tube like?? (Would like to know!)

Would the C&C Box+ be warm?

 

[yklee118]

The C&C Box+ is a great amp however warm is not what I would characterize the sound. Transparent and very dynamic both sonically and detailed representation of the the soundstage. Warmth would not be characterized with this amp with the stock OP-amp, however though if you are looking for bit of warmth, I highly recommend the C&C F1 (can drive headphones of up to 300-ohms only don't go past three o-clock or distortion will occur since this amp performs best at below 150-ohms) since the overall soundstage will be presented in full form with a slight hint of warmth in overall upper and lower frequencies. I own this unit driving the ATH-W1000 and the Sennheiser HD280 Pro.

 

[amb]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif It's not very warm; AD8397 has always sounded kind of sharp to me.

It's worth noting that not every amp that uses a particular opamp would sound the same. One of the recent Go-Vibe amps also use the AD8397/OPA690 combination (same as the high-performance Mini³), but it has definitely a different sound. There are also several other commercial portable amps with the AD8397, yet each also has a different sonic signature. The opamps are a part of the total sonic equation, but so is the rest of the circuit.

The AD8397 is quite a finicky beast to tame. It took many months of experimentation, bench testing, design tweaks and PCB layout adjustments to get it to perform well in a Mini³. While the final schematic is relatively simple, this little amp consumed as much (if not more) development and test time as my far more complex designs.

It's no β22, and you wouldn't expect it to be at less than 1/10 the cost, but treat yourself to an A/B comparison between the two. I think you'd be quite surprised.

 

[jinp6301]

From my time with the mini^3, I feel that its a pretty warm amp. Its no tube amp but it gives nice warmth to my im716s

 

[RedSky0]

I don't have any other amps to compare it too, but it certainly doesn't come off sharp to me, particularly when played from a warm DAP source.

 

[giulio]

I have just got an mini3 built from Rockhopper literally following the parts list on amb's webpage.

I can compare it to a Corda 2Mover and a Pimeta with AD744 (in class A using pin 5) and buf634 buffers. This is not so different from the LISA apart from the discrete buffer.

Compared to the mini3 the above are more transparent (subjectively they are more extended on top). I would call the mini3 more laid back (does that equate to warm? You pick). Noticing that the Hornet has got the same opamp and is sometime described as a bit too forward, I conjecture that the difference is partly due to the mini3 having a carbon (rather than metal) film output resistor. I am pretty sure both amps are well optimized.

All in all, the mini3 with the carbon film output resistor is not forward though not warm in the sense normally associated with valve amps.

All the above amps are highly recommended.

Best
Giulio

 

[majkel]

AD8397 is bright and forward sounding op-amp, OPA690 is darker and with longer decay but having not impressive midrange timbre. Of course, you can adjust the sound of the amp choosing the electrolytic caps of different flavors but the AD8397 sets the limit IMHO at some level, and no warm, mellow and alluring sound is to obtain here.
There is also a disadvantage of using the OPA690 in the ground channel - it's only 190mA DC capable, so you limit the current efficiency of the whole amp to 95mA peak per channel. So, using the AD8397 is kind of redundant.
Search some Polish websites for MxM schematic. This is a design allowing to take full advantage of AD8397 current capabilities which is a good thing when using low impedance headphones. The MxM might bit fitted to the smallest Hammond 1455 series enclousure. The PCB layout should be available as well, just look up forum.MP3store.pl (Powered by Invision Power Board)